The invention relates to a pulsed gas laser apparatus such as a gas laser generator, a gas laser amplifier or a gas-filled wavelength converter operated at ambient pressure provided with laser gas supply means and having a tubular open window for in-coupling and out-coupling of a laser beam.
From the AIAA Journal, Vol. 17, No. 11, Sep. 1979, page 1267 high-power lasers which are operated under atmospheric pressure and have so-called "Free-Vortex Aerodynamic Windows" for the out-coupling of the laser beams are known. The particular design features of such windows are known from U.S. Pat. No. 3,936,771 or German Patent DE 3701718C2. Basically, there is provided some kind of gas curtain which extends across the window so as to separate the laser gas from its surroundings.
The magazine "Laser Und Optoelektronik" 21 (4) 1989, on pages 67 to 71 describes an aerodynamic window with axial gas flow (p. 67) for CO.sub.2 high-power lasers which have discharge or resonator chambers with internal pressures of typically 100 m bar. With such a window which operates in principle like an ejector, there is an unavoidable loss of laser gas which needs to be replenished constantly. This type of window as well as the type described first require powerful pump or compressor systems with all the concurrent expenditures.
It is the object of the present invention to provide a laser apparatus of the type described with design features that simplify the apparatus and operational requirements for maintaining separation at the window between the laser gas and the ambient gas.